The present invention relates to a process for the production of a novel self-swelling leakage-preventing material capable of swelling by absorption of water and preventing leakage of water by clogging interstices.
In public works and construction works, cracks, cleavages or interstices often form in the places where mortar or concrete has been applied or wherein water-supplying pipes are jointed, and often make a cause of leakage of water. In the prior art, such cracks or interstices are filled with a leakage-preventing material based on rubber, plastics and bitumen, such as rubber packing materials, rubber sealants and bitumen jointing materials. During the use for a long period of time, these materials tend to permit deterioration of the materials per se or formation of interstices due to change in size of interstices in the structure to which the meterials had been applied so that leakage of water may again occur in the place to which the materials had been applied. A leakage-preventing material of such type as can be swollen with the passing out water and can seal interstices or pores to stop leakage of water was also proposed to overcome the drawbacks caused by the above mentioned materials per se. However, such material also cannot stably be used for a long period of time because of its poor swelling rate and poor gel strength. Thus, there has not yet been found a practically advantageous leakage-preventing material in this art.
As a result of extensive researches made to develop a leakage-preventing material which is easily capable of being swollen with water and has satisfactorily high gel strength and swelling rate and which can maintain these useful properties stably for a long period of time, it has now been found that such purpose can be achieved by subjecting a copolymer having acid anhydride residues, a polymer emulsion having compatibility with the copolymer and a polyhydric or polyfunctional compound to crosslinking to form a crosslinked product having a desired swelling rate. The present invention has been accomplished on the basis of the above finding.